Gear system

ABSTRACT

A gear system has a planetary gear (5) mounted on a conical main shaft (8) in such a manner to move axially thereon, the planetary gear being in meshing engagement with a central gear (3). A receiving device is provided to receive thrust generated at the planetary gear (5). When a plurality of planetary gears (5) are employed, a clearance (S) formed between the surface of the conical main shaft (8) and an inner peripheral surface of a bearing (17) of each planetary gear (5) is changed according to the axial position of each gear (5) on the conical shaft (8) under the influence of a thrust counterbalancing device. Thus, a distance between the center axis of the conical shaft (8) and that of the planetary gear (5) is thereby increased or decreased to effect even application of load to each planetary gear (5).

BACKGROUND OF THE INVENTION

This invention relates to a gear system and is particularly concernedwith a gear system such as a planetary gear system wherein a pluralityof gears are in meshing engagement with the central gear, transmissionpower being equally divided into said plurality of gears.

As an example of such gear system, there has hitherto been known a speedreducing mechanism for use in connection with a geared motor as shown inFIG. 1. In such a speed reducing mechanism, an input shaft 2 supportedin a motor casing 1 is operatively associated with an external gear 3which serves as a sun gear. Three planetary gears 5 are disposed betweenthe external gear 3 and a stationary gear 4 for meshing purposes.Associated operatively with an output shaft 7 is a carrier 6 adapted torotatably support the planetary gears 5. Now, in such a planetary gearmechanism, assuming that central distances L1 between the respectiveadjacent planetary gears are exactly coincident with each other andcentral distances L2 between the external gear 3 and the adjacentplanetary gears are also exactly coincident with each other as shown inFIG. 2, the planetary gears are disposed in equal spaced relationshipwith each other. Therefore, load is evenly applied to the respectiveplanetary gears 5 provided that the respective gears 3, 4 and 5 have noerror. Thus, these gears 3, 4 and 5 may be operated as positively asexpected. In practice, however, coincidence of each of the centraldistances L1 and L2 is hardly accomplished. Furthermore, bearingportions of the respective planetary gears 5 and the gears 3, 4 and 5are naturally never free of errors. As a consequence, even applicationof the load is hardly effected and power is not equally divided. Inaddition, there is a disadvantage that noises occur due to vibrations ofthe whole speed reducing mechanism.

SUMMARY OF THE INVENTION

This invention has been made in order to overcome the foregoingdisadvantages and has for its object to provide a gear system whichpermits even application of load to a plurality of gears meshing withthe central gear so as to ensure equal division of power and whichprevents occurrence of noises due to vibrations thereof.

Another object of the invention is to provide a gear system which iscompact and is readily incorporated into a wide variety of machines.

A further object of the invention is to provide a gear system which issimple in construction and is readily and economically manufactured.

Yet another object of the invention is to provide a gear system whichprevents disorder of gears upon generation of excessive thrust.

According to this invention, the planetary gear 5 is mounted on the mainshaft 8 (hereinafter, referred to as a conical shaft) in such a mannerto move axially thereon, said planetary gear 5 being in meshingengagement with the gear 3. Thrust in the direction of the smalldiameter end of the conical shaft 8 is generated at the gear 5 dependingupon variations in load applied to the gear 5. A receiving means isprovided to receive the gear 5 movable in the direction of the smalldiameter end of the conical shaft 8. The receiving means may also serveas a thrust measuring means to measure the amount of the thrustgenerated at the gear 5.

Also, according to the invention, a plurality of gears 5 may beprovided. In this case, the receiving means also serves as a thrustcounterbalance means to provide equal application of load responsive tothe thrust generated at the respective gears 5. Under the influence ofthis thrust counterbalance means, as the axial position of the gears onthe shafts 8 is changed, a clearance S formed between the surface ofeach shaft 8 and the inner peripheral surface of bearing 17 of each gear5 is changed accordingly. Consequently, the center axis of each conicalshaft 8 is deviated from that of each gear 5. In this state, load isreduced in the gear with now high load applied thereto whereas load isincreased in the gear 5 with now low load applied thereto. Hence, equalload is applied to the respective gears 5 and power is equally dividedthereinto, thereby drastically reducing noises.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view of a speed reducing mechanism for use in ageared motor;

FIG. 2 is a schematic view showing a planetary gear mechanism only, inthe speed reducing mechanism;

FIG. 3 to FIG. 14 respectively show a first embodiment of the inventionand FIG. 3 is a front view of a planetary gear mechanism;

FIG. 4 is a vertical sectional view of the planetary gear mechanism;

FIG. 5 is a front view of a backing plate;

FIG. 6 is a sectional view of the backing plate;

FIG. 7 is a front view of a thrust backing plate;

FIG. 8 is a sectional view of the thrust backing plate;

FIG. 9 a sectional view, in part, showing the manner in which aplanetary gear is centrally positioned on a conical shaft;

FIG. 10 a sectional view taken along the line I--I of FIG. 9;

FIG. 11 a sectional view, in part, showing the manner in which theplanetary gear is positioned closer to the large diameter end of theconical shaft;

FIG. 12 is a sectional view taken along the line II--II of FIG. 11;

FIG. 13 is a sectional view, in part, showing the manner in which theplanetary gear is positioned closer to the small diameter end of theconical shaft;

FIG. 14 a sectional view taken along the line III--III of FIG. 13;

FIG. 15 to FIG. 24 respectively show a second embodiment of theinvention and FIG. 15 is a front view of a planetar gear mechanism;

FIG. 16 is a sectional view taken along the line IV--IV of FIG. 15;

FIG. 17 a sectional view taken along the line V--V of FIG.

FIG. 18 a sectional view taken along the line VI--VI of FIG. 15;

FIG. 19 is a front view of a first lever;

FIG. 20 is a sectional view of the first lever;

FIG. 21 is a front view of a second lever;

FIG. 22 is a sectional view of the second lever;

FIG. 23 is a front view of a backing plate;

FIG. 24 is a sectional view of the backing plate;

FIG. 25 is a front view showing incorporation of a lever into a plate ina third embodiment;

FIG. 26 is a sectional view showing incorporation of the lever into thebacking plate illustrated in FIG. 25;

FIG. 27 is a front view showing incorporation of a lever into a thrustbacking plate in a fourth embodiment;

FIG. 28 is a sectional view taken along the line VII--VII of FIG. 27;

FIG. 29 is a sectional view, in part, showing a fifth embodiment of theinvention;

FIG. 30 to FIG. 35 respectively show a sixth embodiment and FIG. 30 is afront view of a planetary gear mechanism;

FIG. 31 is a vertical sectional view of the planetary gear mechanism;

FIG. 32 is a sectional view, in part, showing the manner in which theplanetary gear is mounted on the conical shaft under low loadingconditions;

FIG. 33 is a sectional view taken along the line VIII--VIII of FIG. 32;

FIG. 34 is a sectional view, in part, showing the manner in which theplanetary gear is mounted on the conical shaft under high loadingconditions;

FIG. 35 is a sectional view taken along the line IX--IX of FIG. 34;

FIG. 36 is a sectional view showing the manner in which the planetarygear is mounted on the conical shaft according to a seventh embodimentof the invention;

FIG. 37 to FIG. 41 respectively show an eighth embodiment of theinvention and FIG. 37 is a front view of a planetary gear mechanism;

FIG. 38 is a vertical sectional view of the planetary gear mechanismshown in FIG. 37;

FIG. 39 is a perspective view of a common support ring;

FIG. 40 is a perspective view of a wave ring spring;

FIG. 41 a view showing the wave ring spring in use;

FIG. 42 is a schematic view of a gear system according to a ninthembodiment of the invention;

FIG. 43 and FIG. 44 are sectional views, in part, respectively showingthe manner in which gears are mounted on the conical shaft according tothe above embodiment;

FIG. 45 shows a tenth embodiment of the invention;

FIG. 46 to FIG. 49 are perspective views respectively of bellevillesprings; and

FIG. 50 is a perspective view showing another example of a ring spring.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The invention will now be described in greater detail with reference toillustrative embodiments shown in the accompanying drawings.

In this invention, the gear 5 is moved under thrust in the direction ofthe small diameter end of a main shaft 8 of conical configuration(hereinafter referred to as a conical shaft) as greater power is dividedinto the gear 5, and is, then, received by a receiving means which alsofunctions to counterbalance the thrust applied thereto. It should bementioned, therefore, that such receiving means will be described withreference to a thrust counterbalance means.

In a first to a fourth embodiment, the gear 5 having a lesser amount ofdivisional power is forcedly moved in the direction of the largediameter end of the conical shaft 8 by means of a thrust counterbalancemeans constructed of a lever and/or a thrust backing plate to therebytransmit more power. On the other hand, the gear 5 which now has agreater amount of divisional power is forcedly moved in the direction ofthe small diameter end of the conical shaft 8 by means of the same tothereby reduce the amount of power to transmit. In this manner, theplurality of gears 5 have the same thrust and thus, transmit an equalamount of power.

Reference is now made to FIG. 3 to FIG. 14 respectively illustrating thefirst embodiment of the invention. As shown in FIG. 3 and FIG. 4, thethree conical shafts 8 (only one shaft is shown in FIG. 4) are fixed toone side of the carrier at 120° intervals. Fixed to the front end ofeach of the conical shafts 8 is a backing plate 9, as shown in FIG. 5and FIG. 6. The backing plate 9 is formed with a spherically concavedsurface 10. Fitted slidably in the concaved surface 10 of the backingplate 9 is a spherically convexed surface 12 of a thrust backing plate11 acting as a thrust counterbalance means shown in FIGS. 7 and 8. Thethrust backing plate 11 is formed with three spherically concavedsurfaces 13 at 120° intervals in the opposite direction from theconvexed surface 12. Fitted in this concaved surface 13 is a washer 14having a spherical surface, which is, in turn, in contact with theplanetary gear 5. Incorporated between the planetary gear 5 and thecarrier 6 are a washer 15 and a resilient member 16. It will be notedthat a helical spring is employed as the resilient member 16.

In such an arrangement, when different thrust in a direction of thesmall diameter end of the conical shaft 8 occurs at the three planetarygears 5, the thrust backing plate 11 is free to move in an inclinedmanner. Accordingly, the planetary gear 5 having greater thrust is movedtoward the small diameter end of the conical shaft 8, whereas theplanetary gear 5 having lesser thrust is moved toward the large diameterend thereof.

As set forth above, when the planetary gear 5 is moved toward the smalldiameter end of the conical shaft 8, load applied thereto decreases andthus, the thrust becomes less. On the other hand, when the planetarygear 5 is moved toward the large diameter end of the conical shaft 8,such load increases and thus, the thrust becomes large. Therefore, asthe thrust occurring therein becomes equal, the load may equally beapplied thereto and equal transmission of power may be effected.

Reference is further made to FIG. 9 to FIG. 14 showing variations intransmission power upon axial movement of the planetary gears 5.

When the planetary gear 5 is moved to such a position as shown in FIG.9, the center axis of the planetary gear 5 is located eccentrically fromthat of the conical shaft 8 in such a driving direction as shown by anarrow A by a distance e0 as shown in FIG. 10.

When the planetary gear 5 is positioned at the large diameter end of theconical shaft 8 as shown in FIG. 11, a bearing clearance S becomes smalland a distance el between the center axis of the conical shaft 8 andthat of the planetary shaft 5 becomes lesser. Since the planetary gear 5is moved in the direction opposite to the driving direction shown by thearrow A, more thrust in the direction of the small diameter end of theconical shaft 8 will occur in the planetary gears 5.

When the planetary gear 5 is positioned at the small diameter end of theconical shaft 8 as shown in FIG. 13, the bearing clearance S becomeslarge and a distance e2 between the center axis of the conical shaft 8and that of the planetary gear 5 becomes greater. Since the planetarygear 5 is moved in the driving direction shown by the arrow A, lessthrust in the direction of the small diameter end of the conical shaft 8occurs in the planetary gear 5.

When the planetary gears 5 are driven in a direction shown by the arrowA with respect to the conical shaft 8, a bearing 17 is in contact withthe peripheral surface at one side of the conical shaft 8 via oil in theform of a film.

In the above gear system, as the load is equally applied to the threeplanetary gears 5, safety factors for the planetary gears 5 and othercomponents may be established low, permitting the whole gear system tobe compact.

Also, the three planetary gears rotate under equal loading conditionswhereby noise due to vibrations may be drastically reduced.

In the first embodiment, the number of the planetary gears 5 are threeand a plain bearing is used as the bearing 17 therefor. In the secondembodiment shown in FIG. 15 to FIG. 24, the number of the planetarygears are four and a needle roller bearing with a thrust ball bearing isused. The thrust counterbalance means is constructed for levers 18a, 18band 20, a support of each of which is located at their center.

In FIG. 16, thrust generated in the planetary gears in the direction ofthe small diameter end of the conical shaft 8 is transmitted via thewasher to the first levers 18a and 18b shown in FIG. 19 and FIG. 20.Spherically convexed surfaces 19 formed respectively on the centralportions of the first levers 18a and 18b are fitted into sphericallyconcaved surfaces 21 of a second lever 20 shown in FIG. 21 and FIG. 22.A spherically convexed surface 22 formed at the central portion of thesecond lever 20 as shown in FIG. 16 and FIG. 17 is fitted into aspherically concaved surface 24 of a backing plate 23 (FIG. 23 and FIG.24) fixed to the conical shaft 8.

In FIG. 15, thrust of a planetary gear 5A is balanced with that of aplanetary gear 5B by means of the first lever 18a. Also, thrust of aplanetary gear 5C is balanced with that of a planetary gear 5D by meansof the first lever 18b, the total force, the thrust of the planetarygear 5A plus that of the planetary gear 5B is adapted to act on ajoining portion 20a (spherically concaved surface 21 and sphericallyconvexed surface 19) where the first lever 18a is fitted in the secondlever 20. Further, the total force, the thrust of the planetary gear 5Cand the planetary gear 5D, is adapted to act on a joining portion 20b(spherically concaved surface 21 and spherically convexed surface 19)where the first lever 18b is fitted in the second lever 20. As thesecond lever 20 is supported by the backing plate 23 via the sphericallyconvexed surface 22, the force acting on the joining portion 20a isbalanced with that acting on the joining portion 20b. As a result, thesame amount of thrust may be generated in the four planetary gears 5A,5B, 5C and 5D respectively, thereby effecting equal distribution ofpower.

Reference numeral 25 in FIG. 16 designates a belleville spring as aresilient member.

In the third embodiment shown in FIG. 25 and FIG. 26, the number of theplanetary gears 5 used is two. Thrust generated in one of the planetarygears 5 is applied to the lever 26 through the washer 14 having aspherical surface. This lever 26 is formed at its central portion with aspherically convexed surface 27 which is, in turn, in engagement with aspherically convexed surface 27 on a backing plate 28 fixed to theconical shaft 8 for supporting purposes. In this manner, thrustrespectively generated in the two planetary gears 5 in the direction ofthe small diameter end of the conical shaft 8 is balanced and thus,power may equally be divided. In this embodiment, the thrustcounterbalance means is comprised of the lever 26.

In the fourth embodiment shown in FIG. 27 and FIG. 28, thrustrespectively generated in six planetary gears 5 is balanced by thecombination of three levers 30 and a thrust backing plate 31 havingspherically concaved surfaces 31a into which are fitted sphericallyconvexed surfaces 30a of the levers 30 and inclinedly movably supportedwith respect to the levers 30. Thrust generated in each of the twoadjacent planetary gears 5 of the six planetary gears 5 is balanced bymeans of each of the levers 30. The total force acts on the center ofthe three levers 30 and is applied to three points on the thrust backingplate 31. The thrust backing plate 31 is formed with a sphericallyconvexed surface 32 into which is fitted a spherically concaved surface34 of a backing plate 33 fixed to the conical shaft 8 for supportingpurposes and is, thus, inclinedly movable. Accordingly, thrust generatedin the six planetary gears 5 is balanced and thus, power is equallydivided. In this embodiment, the thrust counterbalance means iscomprised of the three levers 30 and the thrust backing plate 31.

In the fifth embodiment shown in FIG. 29, a hydraulic mechanism isemployed as the thrust counterbalance means. Thrust generated in theplanetary gears 5 is applied to a piston 35 for receiving purposes. Thepiston 35 is fitted in a cylinder 36 which is, in turn, fixed to abacking plate 37 fixed to the conical shaft 8.

In the above arrangement, the thrust generated in the planetary gears 5in the direction of the small diameter end of the conical shaft 8 istransmitted to the piston 35 whereby generation of fluid pressure iseffected in fluid filled in the cylinder 36. The fluid in the cylinder36 is in communication with fluid in the cylinder 36 of the otherplanetary gear 5 by means of a communicating pipe 45. Accordingly, fluidpressure of each of the cylinders 36 is maintained equal and also, thethrust becomes equal, thereby effecting equal division of power.

The communicating pipe 45 is equipped with a pressure gauge M which isadapted to indicate fluid pressure in a fluid circuit. The amount ofthrust to be generated in the planetary gears 5 may, therefore, beconfirmed. In case an excessive amount of thrust is generated in theplanetary gears 5, operation of the gear system may be stopped so as toprevent disorder thereof. The pressure gauge M constitutes a thrustmeasuring means. In a sixth embodiment to an eighth embodiment, a springmember 50 is used as a thrust counterbalancing means for the pluralityof planetary gears 5.

The sixth embodiment will first be described with reference to FIG. 30to FIG. 35. In this embodiment, a support ring 38 is fixed to the frontend of the conical shaft 8 on which the planetary gear 5 is mounted viaa collar 39. The spring member 50 (in this embodiment, a bellevillespring 50 is employed as shown in FIG. 46 to FIG. 49) is disposedbetween the support ring 38 and one side of the planetary gear 5 via acollar 40, said spring member 50 being adapted to urge the planetarygear 5 in the direction of the large diameter end of the conical shaft8. FIG. 32 and FIG. 33, respectively illustrate the planetary gear 5under light loading conditions; namely, the planetary gear 5 iscompressed onto the collar 39 at the large diameter end of the conicalshaft 8 by means of the spring member 50. Under such light loadingconditions, when large load is applied to the output shaft 7, theplanetary gear 5 is moved in a direction of the small diameter end ofthe conical shaft 8 by a distance a as shown in FIG. 34 and FIG. 35. Asa result, the bearing clearance S between the inner peripheral surfaceof the bearing 17 (in this embodiment, a plain bearing metal isemployed) and the outer peripheral surface of the conical shaft 8becomes large and the center axis of the planetary gear 5 is deviatedfrom that of the conical shaft by a distance e. Further, in case alarger load is applied to any one of the planetary gears 5 than theremaining gears, a distance a of which the planetary gear 5 moves in theaxial direction becomes greater for the purpose of reducing such load.For this reason, the distance e in this planetary gear 5 becomes greaterthan that in the remaining planetary gears 5 and retreats in such adirection to reduce the load. In this state, when the load applied tosaid particular planetary gear 5 is reduced, the amount of load reducedis applied to the remaining planetary gears 5. As set forth above, themoving distance a in the axial direction of each planetary gear 5 isautomatically controlled so as to divide power equally into the threeplanetary gears 5. Hence, the thrust generated in the planetary gears 15is balanced with elastic force of the spring member 50 and under theseconditions, the planetary gears 5 are rotated.

Alternatively, the collar 40 may be provided with a piezoelectricelement A at one side thereof facing the planetary gear 5 as shown inFIG. 31. In this case, pressure due to thrust generated in the planetarygears 5 is exerted on the piezoelectric element and the pressure is,then, converted into an electric signal thereby. The amount of thrust isindicated by an ammeter (not shown) in an electric circuit which iselectrically connected to the piezoelectric element A.

In the above arrangement, upon provision of the thrust counterbalancemeans neither spherically convexed surfaces nor spherically concavedsurfaces need be formed and the spring member 50 alone will suffice.Accordingly, the gear system is simple in construction and is easy andinexpensive to manufacture.

In the seventh embodiment shown in FIG. 36, the needle roller bearingwith the thrust ball bearing serves as the bearing 17. A taper sleeve 41is fitted between the bearing and the conical shaft 8. The taper sleeve41 moves on the conical shaft 8, together with the planetary gear 5. Inthis state, the distance e of which the center axis of the conical shaft8 is deviated from that of the planetary gear 5 may be changed so as toeffect equal division of power in the same manner as in the sixthembodiment. While the belleville spring serves as the spring member 50for compressing the planetary gear 5 towards the large diameter end ofthe conical shaft 8 in the sixth embodiment, a helical spring serves asthe same in this embodiment.

In the sixth and seventh embodiments, the resilient members 16 arerespectively independently provided in the planetary gears 5. In theeighth embodiment shown in FIG. 37 to FIG. 41, on the other hand, therespective spring members 50 are integrated into a one piece wave ringspring as shown in FIG. 40. In addition, in the sixth and seventhembodiments, the support rings 38 for supporting the respective springmembers 50 are respectively independently provided in the correspondingplanetary gears 5. In the eighth embodiment, however, these supportrings 38 are integrated into a one piece common support ring as shown inFIG. 39. In the above spring member 50 in the shape of a wave ring,three apertures 42 are formed at 120° intervals and the conical shafts 8are fitted thereinto. The spring member 50 includes crest portions 50aadjacent each of the apertures 42 and trough portions 50b between thecrest portions 50a, thereby forming a wave configuration. Each of thetrough portions 50b bears on the common support ring, while one sidesurface of each of the crest portions 50a is in abutment with one sidesurface of each of the collars 40 which are, in turn, in contact withthe planetary gears 5. In this state, the planetary gears 5 are urgedinto the large diameter end of the conical shafts 8 whereby the crestportions provide elastic force.

Now, as load applied to a planetary gear 5F increases and the springmember is compressed so as to move to the small diameter end of aconical shaft 8F, the spring member 50 is deformed as shown by thebroken line in FIG. 41 to thereby increase thrust under which aplanetary gear 5E and a planetary gear 5G are forced towards largediameter ends of the respective conical shafts 8E and 8G. In thismanner, equal division of power may positively be effected.

Alternatively, a ring spring as shown in FIG. 50 may be replaced by thewave ring spring as the spring member 50. This ring spring is formed atits outer periphery with three arm portions 55 which act as a resilientportion. It will be noted that the ring spring functions in a similarmanner to the wave ring spring.

FIG. 42 to FIG. 44 show a ninth embodiment of this invention. Thisembodiment is applied to a gear system exclusive of the planetary gearmechanism. A plurality of intermediate gears 5H are disposed between theexternal gear 3 fixed to the input shaft 2 and the internal gear 4 fixedto the output shaft 7 for meshing purposes. The intermediate gears 5Hare rotatably supported on the conical shafts 8. As shown in FIG. 44 andFIG. 45, the spring members 50 may be disposed at either the largediameter ends or the small diameter ends of the conical shafts 8, or maybe disposed at both ends thereof. Accordingly, directions of thrustapplied to the intermediate gears 5H may be selected. It will beappreciated that the first to the eighth embodiment is applicable tothis gear system.

FIG. 45 shows a tenth embodiment of this invention. In this embodiment,the spring members 50 are disposed respectively at the large and smallends of the conical shaft 8 so as to urge the planetary gear 5 from bothsides. With this arrangement, the planetary gear 5 is positioned at themiddle of the conical shaft 8. Accordingly, each of the planetary gears5 are movable either to the large diameter end or the small diameter endof the conical shaft 8. Thus, equal division of load may readily beeffected.

It will be appreciated that this invention is not limited to theembodiments as mentioned above, and is applicable to the followingembodiments:

(a) In the above embodiment, the input shaft 2 is operatively associatedwith the external gear 3 as a sun gear via the external gear directlyprovided on the input shaft 2. Alternatively, other associating meansmay be provided between the input shaft 2 and external gear 3. The sameis also true of the case in which the carrier is to be operativelyassociated with the output shaft 7;

(b) A single-stage planetary gear mechanism has been described.Alternatively, two or multistage planetary gear mechanisms may beemployed;

(c) In the first to the fifth embodiments, a combination of aspherically convexed surface and a spherically concaved surface as abearing structure is employed. Alternatively, it may be a combination ofa conical surface and a ball; and

(d) Any number of planetary gears 5 may be used, but at least greaterthan two.

We claim:
 1. A gear system comprising a center gear; a plurality ofgears each having a center axis and each meshing with said center gear;a plurality of main shafts each having an axis and being in the form ofa single cone and each rotatably carrying one of said plurality of gearsdirectly through a bearing having a hole in the form of a single cone, aclearance being provided between an outer surface of each main shaft anda surface of the conical hole associated with each main shaft, wherebyany uneven application of load on a carried gear causes said carriedgear to move in the axial direction of said main shaft because of avariation in the thrust acting in the axial direction of said main shaftresulting from said uneven application of load and also, in accordancewith said axial movement, to move radially becuase of said clearancesuch that the center axis of said carried gear is deviated from the axisof said main shaft; receiving means for receiving said axial thrust; anda thrust counterbalancing means associated with said receiving meansadapted to equalize the load borne by all of said plurality of gears inaccordance with the thrusts acting on said plurality of gears.
 2. A gearsystem as claimed in claim 1, wherein said receiving means includeshydraulic means.
 3. A gear system as claimed in claim 1, wherein saidthrust counterbalancing means is povotally supported at its center andincludes thrust backing plates adapted to receive the thrust of theplurality of carried gears in a position corresponding to the positionof the plurality of carried gears.
 4. A gear system as claimed in claim1, wherein said receiving means includes a spring member.
 5. A gearsystem as claimed in claim 1, wherein said thrust counterbalancing meansis inclined and movably supported at its center and includes a pluralityof levers adapted to receive the thrust of the plurality of carriedgears in a position corresponding to the position of the plurality ofcarried gears.
 6. A gear system as claimed in claim 5, wherein saidthrust counterbalancing means includes a plurality of first leversadapted to receive the thrust of adjacent carried gears via ball-likewashers, each of said first levers having a spherically convexed surfaceformed at a central portion of said first lever, and a second leverhaving spherically concaved surfaces for engagement with the sphericallyconvexed surfaces of the first levers and a spherically convexed surfacefor engagement with a spherically concaved surface of a backing platefixed to the main conical shaft.
 7. A gear system as claimed in claim 5,wherein said thrust counterbalancing means includes a lever adapted toreceive thrusts generated at two of said plurality of carried gearsthrough two washers, said lever being formed with a spherically convexedsurface for engagement with a spherically concaved surface of a backingplate fixed to the main conical shaft.
 8. A gear system as claimed inclaim 5, wherein said thrust counterbalancing means is pivotallysupported centrally and includes thrust backing plates adapted toreceive the thrust of the plurality of carried gears in a positioncorresponding to the position of the plurality of carried gears and theplurality of levers.
 9. A gear system comprising a center gear; aplurality of gears each having a center axis and each meshing with saidcenter gear; a plurality of main shafts each having an axis and aconical form and each rotatably carrying one of said plurality of gearsdirectly through a bearing having a conical hole, a clearance beingprovided between an outer surface of each main shaft and a surface ofthe conical hole associated with each main shaft, whereby any unevenapplication of load on a carried gear causes said carried gear to movein the axial direction of said main shaft because of a variation in thethrust acting in the axial direction of said main shaft resulting fromsaid uneven application of load and also, in accordance with said axialmovement, to move radially becuase of said clearance such that thecenter axis of said carried gear is deviated from the axis of said mainshaft; receiving means for receiving said axial thrust; and a thrustcounterbalancing means associated with said receiving means adapted toequalize the load borne by all of said plurality of gears in accordancewith the thrusts acting on said plurality of gears, said thrustcounterbalancing means being inclined and movably supported at itscenter and including a plurality of first levers adapted to receive thethrust of adjacent carried gears via ball-like washers, each of saidfirst levers having a spherically convexed surface formed at a centralportion of said first lever, and a second lever having sphericallyconcaved surfaces for engagement with the spherically convexed surfacesof the first levers and a spherically convexed surface for engagementwith a spherically concaved surface of a backing plate fixed to the mainshaft.
 10. A gear system as claimed in claim 9, in which each of themain shafts is in the form of a single cone and each of the bearingholes is in the form of a single cone.
 11. A gear system comprising acenter gear; a plurality of gears each having a center axis and eachmeshing with said center gear; a plurality of main shafts each having anaxis and a conical form and each rotatably carrying one of saidplurality of gears directly through a bearing having a conical hole, aclearance being provided between an outer surface of each main shaft anda surface of the conical hole associated with each main shaft, wherebyany uneven application of load on a carried gear causes said carriedgear to move in the axial direction of said main shaft because of avariation in the thrust acting in the axial direction of said main shaftresulting from said uneven application of load and also, in accordancewith said axial movement, to move radially becuase of said clearancesuch that the center axis of said carried gear is deviated from the axisof said main shaft; receiving means for receiving said axial thrust; anda thrust counterbalancing means associated with said receiving meansadapted to equalize the load borne by all of said plurality of gears inaccordance with the thrusts acting on said plurality of gears, saidthrust counterbalancing means being inlcined and movably supported atits center and including a plurality of first levers adapted to receivethe thrust of the plurality of carried gears, one of the levers beingadapted to receive thrusts generated at two of said plurality of carriedgears through two washers, said one lever being formed with aspherically convexed surface for engagement with a spherically concavedsurface of a backing plate fixed to the main shaft.
 12. A gear system asclaimed in claim 11, in which each of the main shafts is in the form ofa single cone and each of the bearing holes is in the form of a singlecone.
 13. A gear system comprising a center gear; a plurality of gearseach having a center axis and each meshing with said center gear; aplurality of main shafts each having an axis and a conical form and eachrotatably carrying one of said plurality of gears directly through abearing having a conical hole, a clearance being provided between anouter surface of each main shaft and a surface of the conical holeassociated with each main shaft, whereby any uneven application of loadon a carried gear causes said carried gear to move in the axialdirection of said main shaft because of a variation in the thrust actingin the axial direction of said main shaft resulting from said unevenapplication of load and also, in accordance with said axial movement, tomove radially becuase of said clearance such that the center axis ofsaid carried gear is deviated from the axis of said main shaft;receiving means for receiving said axial thrust; and a thrustcounterbalancing means associated with said receiving means adapted toequalize the load borne by all of said plurality of gears in accordancewith the thrusts acting on said plurality of gears, said thrustcounterbalancing means being inclined and pivotally supported centrallyand including a plurality of levers adapted to receive the thrust of theplurality of carried gears and further including thrust backing platesadapted to receive the thrust of the plurality of carried gears in aposition corresponding to the position of the plurality of carried gearsand the plurality of levers.
 14. A gear system as claimed in claim 13,in which each of the main shafts is in the form of a single cone andeach of the bearing holes is in the form of a single cone.
 15. A gearsystem comprising a center gear; a plurality of gears each having acenter axis and each meshing with said center gear; a plurality of mainshafts each having an axis and a conical form and each rotatablycarrying one of said plurality of gears directly through a bearinghaving a conical hole, a clearance being provided between an outersurface of each main shaft and a surface of the conical hole associatedwith each main shaft, whereby any uneven application of load on acarried gear causes said carried gear to move in the axial direction ofsaid main shaft because of a variation in the thrust acting in the axialdirection of said main shaft resulting from said uneven application ofload and also, in accordance with said axial movement, to move radiallybecuase of said clearance such that the center axis of said carried gearis deviated from the axis of said main shaft; receiving means forreceiving said axial thrust; and a thrust counterbalancing meansassociated with said receiving means adapted to equalize the load borneby all of said plurality of gears in accordance with the thrusts actingon said plurality of gears, said thrust counterbalancing means beinginclined and movably supported at its center and including three levers,each of said three levers having a spherically convexed surface andbeing adapted to receive the thrust of two adjacent carried gears, and athrust backing plate having on one side spherically concaved surfaces ofthe three levers and on another side a spherically convexed surface forengagement with a spherically concaved surface of a backing plate fixedto the main shaft.
 16. A gear system as claimed in claim 15, in whicheach of the main shafts is in the form of a single cone and each of thebearing holes is in the form of a single cone.